Double casing perforator



April l2, 1932. p, L. SHULL 1,853,239

DOBLE cAsING PRFORATOR Filed Feb. 23, 1928 2 Sheets-Sheet 2 PatentedApr. 12, 1932 UNITED STATES PATENT oEFlcE y DANIEL L. SHULL, OFBAKERSFIELD, CALIFORNIA, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, vTSH'ULL PERFORATING COMPANY, A CORPORATION OF NEVADA DOUBLE CASINGPIERFOlt'ATOIRv Application led February 23, 1928. Serial No. 256,178.

My invention relates to oil well equipment and more particularly tocasing perforators.

After an oil well has been drilled, a casing called the water string isinserted therein, and there is extended into this water string a casingknown as the oil string. For straining gravel and sand from the inwardseeping oil which might injure the oil pump, the oil string is providedwith a screen pipe which extends through the oil sands. The screen pipei's either formed prior to installation of the oil string or else theoil string is perforated, at the level of the oil sands, afterinstallation by a perforator provided for this purpose. It is sometimesdesirable to perforatethe water string also, as when the water stringhas been cemented olf below the oil bearing strata which it is desiredto drain, and it is inconvenient or impossible to raise the lower end ofthe water string to this strata.

It is an object ot my invention to provide a novel casing perforator,adapted to perforate one or more casings.

Since those perforators now in use are not adapted to give the operatora positive indication of the completion of the perforation he oftentimescontinues the operation until the perforations are in the form of longslits which materially weaken the casing and decrease the efiiciency ofthe straining action.

It is another object of my invention to provide a perfor-ttor of theclass described which will give a positive indication to the operatorwhen the casings have been perforated.

It is sometimes necessary to perforate not only the two casings but alsocement around the water string before communication is establishedbetween the oil string and the oil bearing strata.

It is a further object of my invention to provide a perforator of theclass described in which the cutting member has a long throw so that itmay cut out through the formation adjacent to the outer casing.

It is a further object of my invention to provide a perforator in whichthe cutter can be moved into cutting position at any time it is desiredand which will not move Fig. 2 is an enlarged vertical section oftheperforator of `my invention with the cutter in retracted position.

Fig. 3 isa view indicated by the line 3-3 of Fig. 2.

Fig. 4 is a view indicated by the line 4--4 of Fig. 2.

Fig. 5 is a vertical section similar to Fig. 2 except that the cutter isreleased and in cutting position.

Fig. 6 is a vertical section of part of the body portion of myperforator showing the position of the cutter at the completion of theperforation.

Fig. 7 is a vertical sectional view of the cylindrical sleeve of thetrip cage of my invention indicated by the line 7 7 of Fig. 4.

Fig. 8 is a view indicated bythe line 8--8 of Fig. 7

Referring to the drawings and particularly to Fig. 1, a well 11 has beendrilled by apparatus supported upon a derrick 12 and an outer casing orwater string 13 has been inserted in the well and cemented oil'l at itslower end as indicated at 14. The upper end of the casing 13 is providedwith a casing-head 15 forming a tight fit between the water string 13and an oil string 16 which is extended inside the water string. When itis desired to permit oil to flow into the oil string 16 at a level abovethat at which the water string is cemented ofl", as at an oil stratum17, a perforator 18 of my invention is attached to the lower end of ajar 19 and associated weight 20, and lowered on a cable 21 through t-heoil string 16 into the position shown in Fig. 1.

The jar and weight mechanism may be of the conventional type well knownin the art,

comprising two interlocking links 22 with n. ram or weight 23 attachedto the upper link.

The rforator 18 includes a body 24 cylindrical 1n cross-section, asillustrated in Figs. 3 and 4, with a coupling 25 at its upper endadapted to threadedly receive the lower end of a link 22 of the jarmechanism 19. The lower end of the body 24 has a cylindrical hub 26 oflesser diameter than the body 24, and this hub is provided with externalthreads 27 for a purpose to be described later.

Formed diametrically in the body 24 and with its axis parallel to theaxis of the perforator 18 is a cutter slot 28 having a vertical', aninclined, and an arcuated wall, as indicated by the numerals 29, 30 and31 respectively in Figs. 2, 5 and 6. At right angles to the cutter slot28 a cam slot 32 extends through the body 24, this cam slot comprising aportion 33 and a portion 34 substantially parallel to the verticalportion 29 and the inclined portionl 30 of the cutter slot 28.

Positioned in the cutter slot 28 is a cutter 35 non-rotatably mounted ona cutter shaft 36 slidably disposed in the cam slot 32, the cutter shaft36 being of a length which prohibits its projection outside the body 24at any position in the cam slot 32 for obvious reasons. The cutter 35comprises a blade portion 37 with an arcuated lower edge 38 and acutting edge 39, and a plate portion 40. The plate portion 40 isprovided with a flat edge 41 at approximately a right angle with theblade portion 37 and an arcuated portion 42 of downwardly inclined teeth43, and the whole cutter 35 is so mounted on the cutter shaft 36 as topermit substantially the entire edge 41 of the plate 40 to bear againstthe vertical portion 33 and the inclined portion 34 of the cam slot 32when the cutter 35 and shaft 36 are properly rotated.

The external threads 27 of the cylindrical hub 26 at the lower end ofthe body 24 are adapted to screw into internal threads of a hollowcylindrical sleeve 44 of a trip cage 45. Threadedly secured in the lowerend of the sleeve 44 is an end plate 46 with a central cylindrical bore47 through which a trip shaft 48 is adapted to slidably extend. Re'-tained in threaded engagement with the upper end of the trip shaft 48 asby a lock nut 49 is a trip plate 50 with an arcuated slot 51 formedtherein, as illustrated in Figs. 4 and 8. Threadedly secured to the triplate 50 in the arcuated slot 51 is a pin 52 wliich extendsinto a groove53 formed by two lips 54 and 55 projecting inward from the cylindricalsleeve 44. The lip 55 has an inclined portion 56 extendingr toward andbeyond the lip 54 and the lip 54 ends a short distance above thisinclined portion 56 as clearly illustrated in Fig. 7. Pivoted to theinterior of the cylindrical sleeve 44 immediately under the lower end ofthe lip 54 is a gate 57 whose lower end 58 is adapted to engage theinclined portion 56 vof the lip 55 when the gate 57 4is in a vertendingto retain the gate 57 in a vertical or closed position is a flat spring59 attached to the lip 54 as by a screw 60. An o ning 61 in thecylindrical sleeve 44 permits thee gate 57 to swing open to allow thepin 52 to move out of the roove 53 and also permits the operator to sett e pin 52 back in the groove 53 at the conclusion of the' operation.Supported on the trip late 50 is an operatin pm 62 which is slidab ydisposed in a cylin rlcal bore 62a in the body 24 to the cutter slot 28.The operating pin 62 is provided with a hub 63 at its lower end and ahead 64 at its upper end, both of which are of greater diameter than thebore 62' so that the movement of the pin 62 in the bore 62* is limited.

Threadedly secured to the lower end of the trip shaft 48 is acylindrical stop member 65 slidabl disposed in a cylindrical sleeve 66which is t ireadedly attached. at its lower end to the spring-retainingsha''t 67. Disposed between the cylindrical stop member 65 and thespring-retaining shaft 67 in the cylindrical sleeve 66 is a coil spring68 which acts as a shock absorbing member for the pin 52 in the top ofthe groove 53 during the downward passage of the perforator 18 in thecasin'g 16. It should be obvious that the trip shaft 48 is free torotate relative to the springretaining shaft 67. Attached as by screw tothe spring-retaining shaft 67 are flat springs 70, here shown as four innumber, adapted to frictionally and resiliently engage the inner surfaceof the oil string 16.

The operation of my invention is as follows:

The cutter 35 is placed in the osition shown in Fig. 2, and the pin 52is p aced in the groove 53, and the apparatus with its associated jar 19and weight 20 is lowered on the cable 21 into the oil string 16 to thelevel at which it is desired to perforate the casings. During thedownward travel of the perforator 18 the pin 52 is retained in the topof the slot 53. The spring 68 absorbs the shocks caused by anyirregularities in the casing which might prove detrimental to the pin52.

When the apparatus is at that level at which it is desired to o eratethe cutter 35, the cable 21 is subjecte to an upward pull. Because ofthe engagement of the flat springs 70 with the casing 16 this causes arelative movement between the body 24 and the spring-retaining shaft 67so that the springretaining shaft 67, the trip shaft 48, and the tripplate 50 move downward relative to the body 24 and the cylindricalsleeve 44 until the pin 52 contacts the inclined portion 56 of vthe lip55 in the groove 53. The continued upward pull on the cable 21 causesthe pin 52 to move downward on this inclined surface 56, through theswing gate 57 as indicated by the dotted lines 71 of Fig. 7 and intoltical or closed position. Bearing against and the position shown by thedotted lines 72 of thel same figure. After the passage of the pm v52 thegate 57 is closed by the pressure of the flat spring 59 to prevent theentrance of `the pin 52.

tive to the body 24 and the sleeve 44 so that it engages the operatingpin 62 and causes it to move the cutter 35 into the position shown inFig. 5.

As the weight is raised and dropped by the cable21 the .cutting edge 39of the cutter blade 37 is forced into the casing 16. Each successiveblow on'the perforator 18 causes the cutter to move upward relative tothe body 24 in the cam slot 32. Because of the inclined portion 34 of.the cam slot 32 this relative movement forces the cutter blade 37further into the casing 16. The teeth 43 of the plate portion of thecutter 35 engage the innner surface o f the casing 16 to retainthe'blade portion 37 in proper cutting position. The pounding act-ion iscontinued until both casings and the formation immediat-ely adjacentvare perforated. It should be noted that because of the fact that thecutter 35 is operating through a circular swing the cutter blade 37 hasan exceptionally long throw so that any cement or non-porous formationadjacent to the outer casing can also be perforated.

When the cutter blade 37 has finished the perforation, the cutter shaft36 will be at the top of the inclined portion 34 of the cam slot 32. Atthis time the body 24 and associate j ar 19 and weight 20 will dropuntil the eutter shaft 36 reaches the top of the vertical portion 33 ofthe cam slot 32, thus giving the operator a positive indication of thecompletion of the perforation.

The perforator 18 is then pulled upward, the cutter shaft 36 sliding inthe inclined portion 34 of the cam slot 32 and removing the cutter blade37 from the perforation. The frictional engagement of the flat Springs70 with the casing 16 causes the spring-retaining shaft 67, the tripshaft 48 and the trip plate 50 to move downward relative to the body 24until the pin 52 is in the position shown by the dotted lines 72 of Fig.7 when the whole apparatus moves upward as a unit. The downward movementof the trip plate 50 relative to the body 24 permits the operating pin62 to assume the position shown'in Fig.

2 so that the movement of the cutter shaft 36 in the inclined portion 34of the cam slot 32 may continue until the cutter 35 assumes the positionshown in Fig. 2 in which it offers no resistance to the upward movementof the perforator. This upward movement of the apparatus is continueduntil that level is reached at which another perforation is made. Thecutter 35 is moved into operating position in this .second location bysimply lowering the Weight 20. The fiat springs retain the trip plate5'0. in the same position while the body 24 is lowered" until the tripplate 50 causes the operating pin 62 to move the cutter 35 into cuttingposition. Thereafter the operation is identical with that alreadydescribed.

IVh'en the perforator 18 has been removed from the casing` 16, the gate57 is moved into an open position in the opening 61 in the cylindricalsleeve 44 and the pin 52 is moved into the groove' 53. The perforator isthen ready to again be lowered into a Well.

While the preferred form ofv embodiment of my invention aboveillustrated and described is fully capable of fulfilling all ofthepurposes primarily stated, I do not Wish to be limited to it, for it isrto be understood that my invention may be embodied in various otherforms, all coming within the scope of the claims which follow.

I claim as my invention:

1. In a casing perforator, the combination of: a body; cam slots formedin said body,

said cam slots comprising an inclined and a vertical portion; a cuttermounted in said body on a shaft between said-cam slots, said cutterbeing adapted to permit said body to drop when said shaft is in saidvertical portion of said cam slots following the cutting operation; andAmeans for moving said cutter along said inclined portion of said camslots.

2. In a casing perforator, the combination of: a body; cam slots formedin said body, said cam slots comprising an inclined and a verticalportion; a shaft supported between said cam slots; a cutter adapted tocut two strings of easing mounted on said shaft, said cutter being soformed as to permit said body to fall the length of said verticalportion of said cam slots when the perforation is completed; and meansfor so moving said shaft along said inclined portion of said cam shaftsas to cause said cutter to perforate said casings.

3. In a casing perforator, the combination of: a body; cam slots formedin said body, said cam slots comprising an inclined and a verticalportion the vertical port-ion being arranged above the inclined portion;a cutter shaft extending between said cam slots; a cutter mounted onsaid cutter shaft between said cam slots, said cutter being adapted tocomplete the perforation of two strings of casing while said cuttershaft is in said inclined portion of said cam slots; releasing means formoving said cutter into operative position; locking means for preventingthe functioning of said last named means until said body is moved upwardrelative to said releasing means; and means adapted to so frietionallyengage said casing as to permit the upward movement of said body to berelative to said releasing means.

4. In a casing perforator, the combination of: a body; cam slots formedin said body, said cam slots comprising an inclined and a verticalportion; a. cutter shaft extending between said cam slots; a cuttermounted on said cutter shaft between said cam slots, said cutter beingadapted to complete the perforation of two strings of casing while saidcutter shaft is in said inclined portion of said cam slots; a pinadapted to move said cutter into operatingr position; a plate adapted toactuate said pm; a pin and groove mechanism so associated with Saidplate as to prevent the actuation of said pin until said body is movedupward relative to said plate; and spring means associated with saidplate, said spring means being adapted to cause said body to move upwardrelative to said plate when said body is moved upward in said casino'.

5. In a casing perforator, the combination of a body, cam slots formedin said body, said cam slots comprising an inclined portion and avertical portion thereabove, a cutter mounted in said body on a shafftbetween said cam slots, said cutter including a blade portion having acutting edge and a plate portion having an arcuate surface providingpipe engaging means, the cutting edge and the pipe engaging means ofsaid cutter being adapted to engage the pipe to be perforated todetermine the position of engagement of the cutting edge of said cutterwith the pipe, and means for initiating movement of said cutter alongsaid inclined .portion of said cam slot.

6. In a casingperforator, the combination of a body, a cutter supportedby the body, said cutter including a blade portion having a cutting edgeand a plate portion of arcuate surface thereabove for frictionallyengaging the pipe to determine the position of engagement of the cuttingedge with the pipe, means for pivotally supporting the cutter, and meansfor moving the pivotal support of said cutter outwardly as the body isdropped relative to said pipe to cause the cutter to be thrust outwardlyfrom the body.

7. In a casing perforator, the combination of a body, a cutter supportedby the body, said cutter including a blade portion having a cutting edgeand a plate portion providing means for engaging the pipe to determinethe position of engagement of the cutting edge with the pipe, means forpivotally supporting the cutter, means for moving the pivotal support ofsaid cutter as the body is dropped to cause the cutter to be thrustoutwardly from the body, and means adapted to be actuated only duringthe first portion of the drop of said body to move the cutter so thatthe cutting edge of the blade portion and the engaging means of theplate vportion engi the pipe.

8. In a casing perforator the combination of; a body, a cutter mountedin said body and normally positioned within said body, means' forfrictionally engaging a casing, means responsive to downward movement ofsaid body relative to said frictional means for forcing said cutteroutward from said body and through a casing, 'locking means forpreventin such relative movement of said body, an frictional engagingmeans, and means responsive to upward movement of said body relative tosaid frictional engaging means for releasing said lockin means.

9. In a casing perforator the com ination of; a body, a cutter mountedin said body and normall positioned within the lower part of said bo y,means for ejectin said cutter laterally from said body where y itengagesthe casing, and means for forcing said cutter through said casingin response to downward movement of said body throu h a predetermineddistance relative to sai casing, said means thereafter permittingfurther permitting further downward movement of the body with respect tothe casing throu h an additional predetermined distance wit out furthermovement of said cutter through the casing.

10. In a casing perforator the combination of; a body, cam slots formedin said body having lower inclined portions and upper vertical portions,a cutter mounted in said body .between said cam slots and having meansengaging with said slots, said means normally engaging the lower ends ofsaid slots whereby said cutter is maintained within said body, meansresponsive to downward movement of said body relative to an enclosingcasing for initiating movement of said cutter upward in said slots toengage it with said casing whereby further downward movement of saidbody relative to said casing forces said cutter along said inclinedslots to project it through the casing and thereafter along the straightportions of said slots to permit relative movement of said body andcutter without further penetration of the cutter in the casing.

In testimony whereof. I have hereunto set my hand at Los Angeles,California, this 17th day of February, 1928.

A DANIEL L. SHULL.

